On Nov 21, 4:20 pm, wrote:
Hi. thanks for the detiailed response JF.

I'm using the following solenoid:www.radionics.ie: RS Part number
search (top of page): 431-7560
(19mm push, 12V)

I'm looking at about 3.5% duty cycle.
It says on the datasheet(http://docs-europe.electrocomponents...900766b805c2a1...)
that the wattage increase by the square of the increase in voltage.
12-72 = 6x increase so 36x increase in wattage. (1/36 for the duty
cycle)
7W at 100% duty @ 12V so we're looking at 252W on 72V on a 3.6% duty
cycle.

I just measured and found the following:
On a 24V system, the current is 1.1A and the resistance of the
solenoid is about 23ohm.
So sounds like I'll need about 3A current on 72V. That sounds like A
LOT!

Now a far as I understand a wallwart power supply will keep on giving
juice until you reach the maximum current that it's designed for. So
clearly I can't get 3A out of a 1A psu. What about batteries? What
happens if I put 8x9V in series? That will give me 72V but what's the
maximum current that I can draw from it?